Wearable electronic hearing aid having a unitary casing for the batteries and the amplifier



Jan. 24, 1950 s. PosEN ETAL 2,495,476

wEARABLE ELECTRONIC HEARING AID HAVING A UNITARY Y CASING F'OR THE BATTERIES AND .THE AMPLIFIER 3 Sheets-Sheet 1 Filed July 25, 1946 miv N s. w R N m A MMA Wwf. IPN

V MM MH.

PosEN E'r A ING AID HAVING A UNITARY cAsING FoR ,THE .BATTERIES AND THE AMPLIFIER Filed July 25, 194s Jan. 24 1950 s.

' wEARABLE ELECTRONIC HEAR /A/ Vf N TORS. SAM P06` E N 3 Sheets-Sheet 2 Jan. 24, 1950 s. PosEN ET AL WEARABLE ELECTRONIC HEARING AID HAVING A UNITARY CASING FOR THE BATTERIESAND 'I HE AMPLIFIER Filed July 25, 1946 5 Sheets-Sheet 3 #1 gai /2 46 E%\n\\\\'m I /0 I 32 /35 6/ l" dn-.35

63 f d- I ,INVENTORSS SAM ROSE/U BY 'HARVEY E. HANSON Patented Jan. 24, 1950 WEARABLE ELECTRONIC HEARING AID y HAVING A UNITARY CASING FOR THE BATTERIES ANDTHE AMPLIFIER Sam Posen and Harvey E. Hanson, Chicago, Ill.,

assignors. by mesne assignments, to Beltone` Hearing Aid Co., Chicago, Ill., a corporation of Illinois Application July 25, 1946, Serial No. 686,178 y' 17 Claims. (Cl. 179-107) This invention relates to electronic hearing aids of the type wherein the electron tube amplier and the supply batteries therefor are arranged in a common casing which is small enough to be worn in a pocket of the user.

It' is an object of this invention to provide Va hearing aid of the type mentioned which is of a particularly small size and at the same time reduces undesired capacitive interferences to a minimum.

'It is a further object of the invention to provide a hearing aid of the type mentioned wherein atleast one of the supply batteries is used for separating the choke coil or transformer of the electronic amplifier from one at least of the electron tubes of this amplifier.

i Another object of the invention is to provide anelectrostatic shield between the choke coil or transformer of the electronic amplifier and one at least of the electron tubes of this amplifier, using at least one of the current supply batteries as such shielding means.

Another object of the invention is to provide in a, wearable electronic hearing aid wherein the elements of the amplifier are carried by a chassis extending longitudinally of the casing, a lower chamber in said casing delimited by the lower edge of said chassis in such a manner that this chamber will accommodate a rod-shaped battery in horizontal position underneath said chassis and, within a recess of the chassis, a tabletshaped battery above the rod-shaped battery.

` Still another object of the invention is to provide a hearing aid of the type mentioned, wherein metal strips arranged to both sides of the width of the chassis carrying the hearing aid elements extend over the majorv part of the length of the casing and receive between them the terminals of the aforementioned rod-shaped battery, being thereby held at constant potential.

A further object of the invention is to provide a hearing aid of the type mentioned wherein a partition wall projecting from the front wall of the casing towards the back wall thereof is arranged and shaped so as to divide the casing into two dovetailing compartments, the one of said compartments having a lower and an upper section, the lower section extending'across the Whole width of the casing and the upper section 2 extending over a central part only of the width of the casing.

A further object ofthe invention is to utilize the clip commonly provided on wearable hearing aids for establishing an electrical connection between a point within the casing below the partition wall mentioned and a point likewise within the casing but above said partition wall.

Another object of the invention is to provide in a wearable electronic hearing aid which uses a. battery cell of tablet form, a contact structure and housing vfor that battery which will hold the battery positively in position between two contact elements.

f A further object of the invention is to render the just mentioned contact structure and housing for'the tablet-shaped battery self-adjusting in the sense that, when the battery is inserted into the battery housing and left to itself, one of the contact elements will force the battery into a rposition in which it is in intimate contact with the other contact element.

Other objects of the invention 'will appear as the description proceeds, reference being had to the accompanying drawings in which- Fig. 1 is a longitudinal sectional view of one embodiment of the invention;

Fig. 2 is a vertical sectional view on the line 2-2 of Fig. 1;

Fig. 3 is a horizontal sectional view on the line 3--3 of Fig. 1;

Fig. 4 is an elevational back view of the hearing aid with the back cover of the casing removed;

. Fig. 5 is a fragmentary sectional view on the line 5 5 of Fig. 4; n

Fig. 6 is a, fragmentary sectional view on the line 6`B of Fig. 4

Figs. '7, 8, and 9 show a modified form of the contacting and housing structure for the tabletshaped A-battery cell, the three figures showing the cell in three successive stages of insertion into the battery housing; and

Fig. 10 is a fragmentary view similar to Fig. 4 but with a battery housing of the kind shown in Figs. 7, 8, and 9, the tablet-shaped A-battery cell not being inserted.

.f Referring rst to Figs. 1 to 6, the hearing aid comprises a casing A composed of a front cover Ill, a lower back cover Il and an upper back cover l2. The front cover Ill and the lower back 3 cover II are connected at the bottom end of the casing by means of a spring hinge I3 permitting the lower back cover II to be readily opened and closed. Extending across the casing between the side walls I4 and I5 of the front cover IB and integral with this front cover is a partition Wall I6 which divides the casing A into a lower compartment I1 and an upper compartment I8. The partitonwal'l IiSis so arranged xand shaped that4 the lowerl compartmena I1 accommodates: two batteries I9 and 20, I9 being a rod-shaped platesupply B-battery, and 2G a tablet-shaped lila;- ment-supply A-battery. The upper compartment I8 is divided into a frontl space 2jIj anda:

rear space 22 by means of a; chassis: o r-l panel 23 which extends from the top of the casing downto the partition wall I6. The chassis 23w carries on its front side a microphone24 and various,

elements of the electron tube,ampliiiensuchas,

the electron tubes 25, 26 and 21 and the choke coil or transformer 28, whereasA ontherear sida of the chassis 23 other hearing aidI elements are mounted, such as resistors (not shown) avolurne:

control 29, a tone controlcombined with a switch 3A0,Vsgclets 3|, 32dand3,3%.,{011 receiving theterminals of the electron tubes 25, 26an`dj21, re spectivelmetc. The transformer 28` Whosemain po ion is 'situatedAin-V the front space 2| extends With-ite rear. iwrtonhrollgh the. panel. 2.3 into therearspa v22 Itfswillbeunoted thatthe electron tubesv25, 26 and 21 oifthe electronic amplierhave their` bulbs attending parallelrtothe plane ofthe chassiss23 whereasthe socketsl- 3l 3 2; and,33for these tubes are arranged so that .theinaxisextend perpendicularlyto the `planeloi thechassis, The leadiugf. in wires of4 the electron tulc es25,` 26,.and 21 are bent :at a right angle as describedin the ,cepending application Serial No.5'11,2 118, noWU. S. Patent:'No,.. 2,431,198,1of `SainwloesgenT The electron tubesv can thereby. beeasilyvplug ged in and out whenever. replacement becomes, necessary.

As has .been nfientionedk above, the lower compartment I1 which-receives` the batteries I9, and 210,- @wetens with thev upper Compartment I8., in which the electronic amplifier mountedn onthe panel or chassis 2,3., is`V housed. For that purpose, the-partition wall I il; has araised'middle portion |60 so that the lower compartment lflfcomprises an upwardly extending p r jectionor chamberV atan intermediateI portion ofjthe width of the casingrsA. Within ,this fprojection por chamber |10 the tablet-shaped A-battery cell is plgacedwith listens substantially,perpendicular t9 the fromv wall of the casing as well as to the axis of the redt-Shaped Bzbattery I9., Over. thellpwafdlyx tendine portion, 1.6.0; 0f` the partition.. Well lffts a recessin the chassis`23, thevlatter thereby forming two legs 34 vand'35 which ektenddownwardly to oppositesidesvof the projectionv ISI) of the partition wall I6: On (andini the leg 34-of-thechassis 23 there ismounted the transformer, 28' whereas the other leg 35-of-thechassis 23-sup ports the electron tube26 which, preferably,y for-ms the secondstage of the amplifier. i

It will be observedthatthe dovetail varrange-- ment just described'not-only providesfor--a veryY compact; spacesaving construction, butalso secures-a minimum of-couplingbetween the'trans: former 28 andthe tu:be-26^Y of theampliier. By the interposition of the cell-20between the tube '26fandthe-transformer 28, these lattertwoparts are kept at suchrfa'rg-reat distancefromeach otherthat-practically no icouplingL-Will take-place already formthatreason. Furthermore, since-the A-battery has an outer metal shell which is at a constant potential, it will serve as an electrostatic shield between the transformer and the tube 2B. This shielding action of the battery 2D also extends to the tube 25, in regard to which the shielding action of the shell of the battery 20 is supported by the shielding action of the outer shell of the microphone 24 which is situated above the'fifbattery' 2D. Thus the A-battery 2|)V and the microphone 24 separate the transformer 28 and the output tube 21 from the two iirst stages 25 and 26 of the amplifier.

The B-battery I9 which has its terminals 36 Y and ,A31- aty yopposite ends, extends horizontally over the Wholey widtheof the interior of the casing A and, isheld between two contact strips 38 and 39,Y Each of these4 strips 38, 39 extends along one of the two Opposite longitudinal edges of the chassis '23,over the. major part of the length of said edges anddovl'nw-ardly beyond those edges down to the points of contact with the terminals 36- and- 321 ofwthebattery I9. The upper end of :partnfient I8;

the Vmetal strip 38 is secured to the chassis 23 at 40, whereas the upper end of the metal strip 39 is secured to thechassis ZVQLatAI, The points 40 and 4I* connect to some; parts of thel amplifier which are. not shown. The` metalrstrips 38 and 39,- each 0f which is titille#onstaatpotentialv ofv the respective terminalof'lthe battery I9', shield the amplifier sideways against' external disturbances.v

Thev outer shell 43-o f theAA-battery 2jpmakes contactwith a` resilientfcontact kelement 42 which is secured to the back side ofthe chassis 23, whereas the centralu terminal 44` at the top of the-cell 20 makes-contact with acontactplate 4,5

at the inner'surfhace of the frontjwall'l of the casing.- This contactelernent 45 is connected with the conventional clip 46lv ofthe instrument by means-of ar-ivet 41 traversing the insulating ma-v terial of thefront wall= IIjof,` lthe casing. While the contact -elemen-tL45-'Iis situatedunderneath the par-tition-walll; a--conductor481is located above said partition wall and passes-through the-front wall of the'` casing inorderto make contact with the `clip ,45; to Awhiclfi-itis`conductivelyf*secured at 49 by soldering or the like. theconductor 48.leads, as' is show-nin-Fig. 6,' to-an eyelet.A type solder-lug- 50 which nts-into a bush ing.5'|.formed at the .rearside Aofethe front Wall Isof-.thecasing Thebushingl contains an inset/52 having itsaxis-atjfisllig. 1) into which `arscrewA 53 .may beiscrewed :from the backY of the casing, thev backwall I I s beingv thickened at this ypoint1toy form-a. spacing collar 5 4 which, when thescrew 5:3:.is.V screwedIl in,` abuts against the chassis12f3, The screw 53,;passesthrough a hole inv the Lchassis .'23 z and athenv` through a hole in a spring Contact; member 55= carried .byV the front Side Of the Chassez-3;.: Connected withl the. spring Gentech ifrnenlbel;Y sbyfmean-s off,- a, rivet orV the like 56 passing- 4 through .thetchassis 23` isV a conductor. 51, e. g. awirefwhich leadseither directly.v or Via@ some intermediate elements to the switch 30. By tighteningthemscrew 53, the spring Contact member 5.5.1.5 prssed-tieht1yaeainst the lug 50, establishing thereby aH securek electrical 'connection :between fthe conductors Y48 and 51 e sit;

u ,atedtoopposite sides ofthe chassis23 and, in fact; betweenkthe battery'terminal 45" situ-ated next'- t0 the front wallI of thev casing below the partition-wallIfand'the conductor 5*1 which is` lsituatedin therear space 2-2 of-'the upper com- Whileinathe embodiment of the invention Fromthe point 49 shown in Figs. 1 to 6 the .ll-battery '20 is located in a recess of the partition wall IB which is open F at the bottom, the construction may be modied while the battery i9 is removed from the casing.

Figs. 7 to 10 show one form of such a housing for the A-battery. Referring rst to Figs. 'I and 10, l again denotes the front wall of the casing of the instrument and 46 the clip. Part of the front wall ID of the casing forms the bottom I0' of an insulating housing which has a side wall 59 of approximately cylindrical shape and is open at the side opposite the bottom l0' except for a .contact plate 61 which covers up a small portion. of the opening of the battery housing. Secured to the bottom I0' of the battery housing isa .f spring contact member 6l, which is connected to the @up 4e by means of a rivet '41' or the like. The side wall 59 has an inner surface which is partly in the shape of a cylinder whose axis is perpendicular to the bottom I0' and partly in the shape of a cylinder whose axis is at an angle to the axis of the first named cylinder. That portion of the inner surface which is part of a cylinder whose axis is perpendicular to the bottom l0 forms the upper limitation of the cavity in the battery housing and is indicated at 62, whereas the cylinder surface which is inclined relative to the bottom lil' is indicated at 63 and 64.

To insert the battery 20 into the battery housing it is slipped into that housing, using the inclined inner surface 63 as a guide in the manner shown in Fig. '7. The lower edge of the contact plate El is shaped so (along a half circle) that it does not obstruct the insertion of the battery 20. Still using the surface 63 as a guide, the battery cell is pressed forwardly until it assumes the position shown in Fig. 8 in which it compresses the spring contact 6 I. Using the point of contact between the bottom I0' and the cell 2U as a pivot, the battery cell 20 is tilted slightly in counterclockwise direction, bringing thereby the bottom of the cell underneath the projecting edge of the contact plate El. Leaving now the battery 20 to the action of the spring contact 6I, the latter urges the battery 20 into the position shown in Fig. 9 in which it rests against the surface 62 of the inner wall of the battery housing and at the same time is pressed against the xed contact plate el.

The contact spring 6I which in the housing as shown in Fig. 9 presses upon the center of the battery will, as far as the junction point of partsv Y59, 6l is concerned, have the tendency to turnthe battery in counter-clockwise direction. Such turning is, however, made impossible by the fact that in the position of Fig. 9 the cell 20 bears directly against the wall 62 as well as against the wall 63, so that the cell is held wedged between the spring contact 6| and the fixed contact plate 61.

To remove the battery 20 from the battery housing, the battery is pressed towards the bottom' Hl', exerting the pressure not exactly in the center of the cell but at a point below that center whereby the battery is brought into the position shown in Fig. 8 from which it will slip past the fixed contact 61 into the position shown in Fig. 'I from which it can be easily removed.

- `While in;y Figs. 7 to 10 the battery housing is --shown as being completely closed at its lower tip, the lowermost part of this housing may be Cil eliminated, provided a portion of the lower half of the Vhousing is maintained. This will permit the arrangement of the A-battery directly, that is to say without any, spacing, above the B-battery.

While we have shown and described two specic embodiments of the invention, it is to be understood that these embodiments have been given by way of example only, since various changes and modifications may be made in the form and arrangement of the parts of the instru- I ment without departing from the spirit of the invcommon casing small enough to be Worn in a pocket of the user, a chassis in said casing extending longitudinally of the casing over part only of the length thereof and having mounted 'thereon said transformer and said tubes, at least one of said supply batteries being placed between said transformer and one at least of said electron tubes.

2. In a wearable electronic hearing aid, an electron tube amplifier having midget tubes and a transformer, supply batteries for said amplifier, said amplierand batteries being arranged in a common casing small enough to be worn in a pocket of the user, a chassis in said casing extending longitudinally of the casing over part only of the length thereof and having mounted thereon said transformer and said tubes, at least one of said supply batteries being arranged so as to form an electrostatic vshield between said transformer and one at least of said electron tubes.

i 3.V In a wearable electronic hearing aid, an

electron tube amplifier having midget tubes and a transformer, supply batteries for said amplifier,

said amplifier and batteries being arranged in a common casing small enough to be worn in a pocket of the user, said batteries comprising a rod-shaped B-battery and a tablet-shaped A-battery, a chassis in said casing extending Vlongitudinally of the casing from the top end thereof to a line spaced from the bottom of the casing and having a recess formed in its bottom portion so as to leave in said casing a lower 'Y chamber, said rod shaped B-battery being placed at the bottom ofv said chamber with its axis extending horizontally and said tablet shaped A-battery being placed completely above said B-battery within said recess with its axis extendtoo ing also horizontally but at an angle of 909 to said axis of said B-battery and to the plane of said chassis.

4. A wearable electronic hearing aid as claimed in claim 3 wherein the recess of the chassis is situated midway of the width thereof.

'5. In a wearable electronic hearing aid, an

Velectron tube amplifier and supply batteries tending-anne dgesl ofafsaid 'external disturbances;

6.1 In a wearabl'e'electrnicStubehearing aid,

an` e1ectron`==tube amplifierv fand' 5"supply "batterieswallsf and a. partition Awal-l''projecting `from the irontfwall ofthe casingltowardsfthe back'wallfi thereof, said partition wallv f-being 'f' arranged `"and shaped so asv to divide said casingintox-two dove- "er land the lower one said'batteriesfsaid lowerig'fzgm tailing' compartments'- ofvwhich" two'v compartments lthe upper 'one-1accommodates'-A saidl ampliof` fsaid compartments `hav-ing a. lowerwv and an -upper section, said lower:sectionextendingsacross the whole width of i the casingforaccommodating a Blbattery of rodshape Yand 'saidupper section :extending only over :an` intermediatey portion i off,"

Ythewidth ,of1saidzcasing and' dovetailii1g with said 4'upper compartment containing .said ,amplifier, said upper section of said lower? compartment accommodating la tablet-shaped Af'battery having yitsl axisl'perpendicularptofthe 'axis offsaida Bbattery. v Y

7.2 In. ka .fizwearable @electronic` hearing '-aid,f,- an

^ electroni tube; amplifier vand vsupply batteries therefor arranged ;`in:a commonfjcasing -`small enough Ito be. Wo1-nina Apocketofithe. userrsaids:

casingfcomp-rising. a front'iwall; a'back Walkiand sidewalls, .a partition wallzprojecting. from-fsaid front wall towards said'fbackawall,gapchassisfextendingA longitudinallyiof s said 'casing Arfrom the top. thereof down to said partition vwall and dividing the upper portion of said casing into affront and back compartmentyat least; one of saidibatteries being ofV tablet* shape-,andarranged underneath ,said partition wall so Vthat itsxaxisY extends substantially prependicularly-f to: said fronti Wall and :said back iwall, ya -m'etalilc memberr-secured to the outside of said tirentv wallf a contact element at the inner surface ofjsaid frontrwall electricallyV connected through; saidfrontI wall with Y said metallic memberfor contacting one terminal of said battery, when the latter-1 isin place vwithin the; casing, and aconductorfelectrically ,connected to v said 'metallicmember traversing said-'front wall ata pointwithinrsaideasing -which isabove said'partition wall, saidm'etallic member thereby?- establishingV an electrical-,connection between electron tube amplier and supplyfbatteries therefor arranged in.` avvcommon-casing small enough to be wornin a pocket 'ofzthe fuser, said casing comprising a front wall, aback ,-WalL: side walls and a partition wall .projecting fronti-said front wall towards said back-wall,; a chassis extending longitudinally `of --said-A casing from1ythe top thereof down to said partition wallfand dividing ythe upper portion of said #casing- `intera 'front andback compartmenafatleast one offsaid bat-v teries being of tablet shape and arranged-underneathsaid'partitionwall so .that itslaxisveztends substantially .perpendicularlly 4tof-said .front wall ment-ati the inner surface o'fsaidfront wall elec- -itrlcallyl`y connected through said. front wall with said metallic'm'emberffor contacting one terminal `'ofisaid battery; when'the latter is in placezwithin 5 'sthe-'casingg a conductor .electrically connected to said metallic ymember traversing said front wall -atva1poi`nt2 withinsaidcasing which isY above said fpartitioni wall,- said '.metallic member thereby establishing a ani' electrical. connection between fl'fsaid terminal-fof" said battery below said partition 'Wallfandsaid conductor-above said partition Wall, l'saidconductor (':onnectingv further to a Xed con- Ytact' element carried by Isaidffront yWall at the inner sidethereot: a spring 'contact member car- 15niedrby'the front sid'e .of said chassis and adapted `ltofbe pressed against said xed contact member by means; of'a'screw/extending through said back :'plat'e', said-"chassisdand said spring contact memben intdsaidxednontact element, and an elec- .ftricfrconductor behind said chassis' being electriffcal'ly 'connectedfto-said lspring contact member by #mea-na of la connector Ytraversing said chassis.

9,''Inya-:Ywearable electronic hearing aid, an 'electron rtube.- amplier and` supply batteries girtherefor farrangedwin a .common casing small fenonghto'be worn in-alpocket of the user, said casingjcomprisinga front wall,l a back wall, side wallsgsand a partition wall projecting from said frontwall towards saidback wall, a chassis eX- I'tendingf-longitudinallyoi said casing from the top-thereof downto said-partition wall and dividing-the upper portion-of saidcasing into a front 1 andback compartment,fatrleast one of said batteriesbeing oftablet shape-and' arranged underneath said partition'wallso thatA its axis extends substantiallyperpendicularly tosaid front wall andsaidfbackfwalL afmetallic membersecured -toi-Ythe youtsidefofv-.said .front wall, a contact eleff mentat-thef-innersurface oisaid front wall elecwgtricallyrgconnectedthroughsaid front Wall with "said.lmetallic Amember; for contacting one ter- VVVjnri'nal ofrsaid' battery, when-the latter is in place withinrthegcasingga ,conductor electrically con- --nectedto saidfmetallic member traversing said L5Vfront:wallfatwa pointwithin said casing which is yabove said-"partition wall; said metallic member fthereby establishingran velectrical connection between'saiditerminal of `said battery below said partitionwall and said-conductor above said 50,` ipartition .f Wall, :and a contact element secured to the;back side ofvsaidchassis for contacting the fsecondterminal of said battery.

10..-In a Wearable electronic hearing aid, an Y electron tube Y. amplifiery and supply batteries 5521thereor-arranged in-a Acommon casing small enough to be worn in a pocket of the user, said casingfcomprisingfoairont,wall, aback wall, side `walls anda :partition wall projecting from said `fron-tfwall.towards saidback Wall, a chassis exntending.longitudinally of said casing from the top thereof ldownto said partition wall and divid- -ingthefupper,portion ofsaid casing into a front and` back rcompartment, atleast one of said Ybatteries beingof tablet shape` and arranged (id-funderneath said partition wall so that its axis f @extends-.substantially perpendicularly to said front wall and said back Wall, a metallic member vi-securedto ther-outside of said front wall, a conlrtactelement attheinner surfacevof said front 70 =;iwall `velectrically:connected lthrough said front wall -with..said' metallicA member for contacting l' onetermi-nalh of- Saidbattery -whenrthe latter is Y -ingplace ,'within the --casing, a conductor electricallyfgconneoted totl saidmetallic member travers- 75 ing said front.wa1latza pcintwithin said .casing ried lby said front wall at the inner side thereof,

a. spring contact memberv carried bythel front sideof said chassis and adapted to bepressed against said fixed contact member bymeans of fa screw extending through saidback plate, said -chassis and said spring contact member into said fixed contact element, an electric conductor behind said chassis being electrically connected to said spring contact member by means of a connector traversing said chassis, and a contact element secured to the back side of said chassis for contacting the second terminal of said battery.

1l. An insulating battery housing having a side Wall and a bottom and being open at the end which is opposite said bottom, part of the inner surface of said side wall being in the shape of a cylinder whose axis is inclined to said bottom with the exception of a portion of said inner surface adjoining the open end of said housing, which portion is undercut so as to form a surface which is part of the surface of a cylinder whose axis is perpendicular to said bottom and which intersects said inclined cylindrical surface at a distance from said bottom.

12. An insulating battery housing having a side wall and a bottom and being open at the end which is opposite said bottom, part of the inner surface of said side wall being in the shape of a cylinder whose axis is inclined to said bottom with Athe exception of a portion of said inner surface adioining the open end of said housing and extending over a part only of the circumference of said housing, which portion is undercut so as to form a surface which is part of the surface of a cylinder whose axis is perpendicular to said bottom and which intersects said inclined cylindrical surface at a distance from said bottom.

13. An insulating battery housing for a battery cell having a cylindrical shell, said housing having a side wall and a bottom and being open at the end which is opposite said bottom, part of the inner surface of said side wall being in the shape of a cylinder whose axis is inclined to said bottom with the exception of a portion of said inner surface adjoining the open end of said housing and extending over a part only of the circumference of said housing, which portion is undercut so as to form a surface which is part of the surface of a cylinder whose axis is perpendicular to said bottom and which intersects said inclined cylindrical surface at a distance from said bottom, a spring contact secured to saidbottom, and a contact plate at the o-pen top of said housing projecting from the outside beyond the inner contour-line of the top of said housing over a portion of the length thereof, the projecting edge of said contact plate being shaped so as to permit passage of the battery cell into or out of said housing in a position of said cell where its cylindrical shell rests against said inclined cylindrical inner surface of said housing.

14. An insulating battery housing for a battery cell having a cylindrical shell, said housing having a side wall and a bottom and being open at the end which is opposite said bottom, part of the inner surface of said side wall being in the shape of a cylinder whose axis is inclined to said bottom with the exception of a portion no fof :said innerV surface adjoining the open end of `said housingand extendingover a part only of the circumference of said housing, which portion is'unolercut so as to form a surface Which is part of the surface of a cylinder whose axis is perpendicular to said bottom and which intersects said inclined cylindrical surface at a distance :fromsaid bottom, a spring contact secured to vthe bottom of said housing, and a contact plate at the open top of said housing projecting from the outside beyond the inner contour-line of the top of said housing over a portion of the length thereof, the 'projecting edge of said contact plate being yshaped so as to Vpermit passage of the "battery cell into orout of said housing in a position of said cell where its cylindrical shell rests against said inclined cylindrical inner surface of said housing.

l5. An insulating battery housing for a battery cell having a cylindrical shell, said housing having a side wall and a bottom and being open at the end which is opposite said bottom, part of the inner surface of said side wall being in the shape of a cylinder whose axis is inclined to said bottom with the exception of a portion of said inner surface adjoining the open end of said housing and extending over a part only of the circumference of said housing, which portion is undercut so as to form a surface which is part of the surface of a cylinder whose axis is Derpendicular to said bottom and which intersects said inclined cylindrical surface at a distance from said bottom, a spring contact secured to the bottom of said housing, and a contact plate at the top of said housing projecting from the outside beyond the inner contourline of the top of said housing over a portion of the length thereof, the projecting edge of said contact plate being shaped so as to permit passage of the battery cell into or out of said housing in a position of said cell where its cylindrical shell rests against said inclined cylindrical inner surface of said housing, said spring contact being arranged so as to tend to force the battery cell, when the latter is inserted into the housing with the center terminal facing the bottom of said housing, away from the bottom of said housing and against that portion of the wall which is covered up by said contact plate at the top of said housing, establishing thereby contact between said contact plate and said base of said cylindrical shell of the battery cell.

16. A wearable electronic hearing aid as claimed in claim 3, wherein the chassis vhas two downwardly extending legs adapted to receive between them the tablet-shaped A-battery so that one of said chassis legs extends alongside said A-battery to one side thereof and the other of said legs extends alongside said A-battery to the opposite side thereof.

17. In a wearable electronic hearing aid, an electron tube amplifier and supply batteries therefor arranged in a common casing small enough to b-e worn in a pocket of the user, said casing comprising a front wall, a back wall, andV side walls, a partition wall projecting from said front wall towards said back wall, at least one of said batteries being of tablet shape and arranged -underneath said partition Wall so that its axis extends substantially perpendicularly to said front wall and said back wall, a metal member secured to the outside of said fronty wall, a contact element at the inner surface of said front wall electrically connected through said front wall with said metal member for contacting one I terminal of 4said .ibattery when :the 1atter `is -Iplace :Wthinrthe casing, ,and arconductor 4elecitrcally connected. to fsadmetal member-:traverszing, said .front :Wall at; a'. point Wthnisad 1 Leasing -Which is above saidparttonfwall, #said metal rmember thereby establishing van electrlcalrcon- REFERENCES .CITED 4"The followingreferences are of :record inthe4 gleclfths patent: 1

@Number l STATES PATIENTS :Name LDate .Keatng.. --r June 4,.'1901 Meyer Nov. 1,.-192'7 Bly Feb. 22, '1938 .f1-luth@ Oct. 17, 1,939 'Crowley Nov. .3, 1.1942 Culbert Jan. 12, .1943 :Merrill Oct. 26,;-1943 Fordham Oct. 15, :1946 

